Process of making finished circumferentially surfaced lenses from lens stock



X 200/ Cy L035 Oct. 25, 1949. w. J. FLETT 2,485,873

PROCESS OF KING FINISHED CIRCUHFERENTIALLY -SURFACED LENSES FROM LENS STOCK Filed Feb." 5, 1944 INVENTOR WILLIAM J. FLETT Patented Oct. 25, 1949 PROCESS OF MAKING FINISHED CIRCUM- FERENTIALLY SURFACED LENSES FROM LENS STOCK William J. Flett, Washington, D. 0., assignor to the United States of America as represented by the Secretary of the Navy Application February 5, 1944, Serial No. 521,277

1 Claim.

This invention relates to the manufacture of lenses of the type which includes a lens body having substantially opaque surfaces defining a lens face on the body. More particularly, the invention has reference to a novel process of making lenses of this type and which process may be practised expeditiously at low cost.

One object of the invention resides in the provision of a process of making a lens of the character described whereby the lens may be formed with a uniform, arcuate lens face having sharp, finished edges.

Another object of the invention is to provide a process of making a lens of the character described whereby the lens face may be formed without chipping the substantially opaque surfaces defining the lens face.

A further object of the invention resides in the provision of a process of making lenses which is characterized by its simplicity.

Still another object of the invention is to provide a tool for use in forming the lens to receive a mask for defining the lens face.

In accordance with the process of the present invention, the lens is made from a block of lens stock which is formed with a generally arcuate face and with troughs extending along the sides of the face. The arcuate face and the troughs are masked with a suitable opaque material, preferably by painting or spraying the material on the lens block, and the mask is removed from the arcuate face while retaining the mask in the troughs. Thus, the finished arcuate face forms a lens surface which is sharply defined by the mask remaining in the troughs.

For a better understanding of the invention, reference may be had to the accompanying drawing, in which Fig. 1 is a side view of a finished lens made in accordance with the invention;

Fig. 2 is a longitudinal sectional view of a block of lens stock, showing the arcuate lens face and the troughs formed in the block;

Fig. 2A is a perspective view of a tool for forming the lens face and the troughs;

Figs. 3 and-4 are views similar to Fig. 2 showing the mask applied to the lens face and the troughs;

Fig. 4A is a perspective view of a finishing tool for removing the mask from the lens face, and

Fig. 5 is a longitudinal sectional view of the lens showing the lens face exposed by removal of the mask therefrom.

Referring to Fig. 2 of the drawing, the numeral I0 designates a block of lens stock of any suit- 55 able material, for example, a transparent or translucent plastic. According to the process of the present invention, the block I0 is formed with a convex lens face II and with troughs [2 extending along the sides of the face, the troughs being defined in part by side walls l3 extending sharply inwardly from the face I I.

The convex face It and the troughs [2, as shown, are formed by cutting away material from the block Ill, and for this purpose it is preferred to employ the cutting tool shown in Fig. 2A. As there shown, the tool comprises a cutting head [5 having at its end a concave face Ha forming a cutting edge. The cutting head is also provided at its end with shoulders I2a disposed at the sides of the concave face Na and having substantially straight side walls I3a projecting forwardly from the concave face. In the practice of the process, the cutting head I5 is drawn along the block In so that the concave cutting surface Ha forms the convex face II on the block, and the shoulders l2a form the troughs 12 along the sides of the face I I.

The surface of the block is then masked, as shown at I! in Fig. 3, to cover completely the lens face H and the surfaces of the troughs l2. The mask Il may be applied in any suitable manner, as, for example, by spraying or painting an opaque material over the surfaces.

After the masking material I 1 has been applied, the mask covering the lens face H is removed, as shown in Fig. 5. In order to facilitate the removal of the mask from the lens face ll, use is made of the finishing tool shown in Fig. 4A. The finishing tool comprises a head 20 having a concave cutting edge Ila conforming to the shape of the lens face H. In the use of the tool 20, the cutting edge I la is placed on the mask l1 covering the lens face ll (Fig. 4) so that the sides of the cutting edge terminate at and lie flush with the outer ends of the side walls l3 of the troughs l2. The finishing tool 20 is then drawn along the lens face ll parallel to the troughs so as to remove the mask I! from the lens face without disturbing the mask in the troughs. The tool 20 also removes any irregularities on the lens face H, with the result that the finished face H is provided with a smooth surface.

The new process may be used for making lenses of various forms, and for illustrative purposes there is shown in Fig. 1 a toroidal lens made in accordance with the M shown, the lens comprises a hollow lens body [0 having an annular, convex lens face I I defined 3 by the masking material I! in the troughs l2 extending along the sides of the lens face. A

lens of this form is particularly smtal l for use converging ght rays on a photo-sensitive He- 0, the ens 5- finished lens face ll having edges which are 10 chipping the defining edges formed by the mask- 15 ing in the troughs. The process requires only a few simple operations which may be performed by relatively unskilled labor.

What is claimed is:

A process of making a lens from lens stock, 20

which comprises cutting the stock to form a transparent finished circumferential convex lens surface and annular troughs along the sides of said surface, painting the convex lens surface 4 and the troughs with an opaque coating material to form a mask thereon, and removing the mask from the transparent finished convex lens surface while retaining the mask in the troughs, whereby the mask in the troughs defines sharp finished edges on said transparent convex lens surface.

WILLIAM J. FLETT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 221,552 Hanson Nov. 11, 1879 1,085,611 Humbrecht Feb. 3, 1914 1,098,905 Humbrecht June 2, 1914 1,457,804 Wigand June 5, 1923 1,556,566 Wright Oct. 6, 1925 2,137,598 Vos Nov. 22, 1938 2,237,744 Mullen Apr. 8, 1941 2,259,902 McCain Oct. 21, 1941 2,314,838 Kingston Mar, 23, 1943 

